The present invention relates to a sensor for automatic doors. Particularly, the present invention concerns measures to simplify sensor installation.
With respect to an automatic door which opens and closes along a track, an object detection range is usually set on the interior and the exterior of the doorway, and objects in the detection range are detected by an activation sensor. As the activation sensor, there are generally known varieties like sensor mats, ultrasonic sensors and pyroelectric sensors. The activation sensor is turned on when it detects entry of an object within the detection range, and operates to open the door.
Additionally, an auxiliary safety sensor which utilizes a beam (e.g. infrared ray) is installed in the vicinity of the track of the door, between the interior and exterior detection ranges. An example of the auxiliary safety sensor is disclosed in Japanese Patent Laid-open Publication No. 2000-320243. This auxiliary safety sensor is mounted on a pair of posts which stand on both sides of the doorway, in such a manner that a transmitter on one of the posts is positioned face to face with a receiver on the other post. In this structure, when a light beam is emitted from the transmitter towards the receiver and interrupted by something, the receiver fails to receive the light beam. The sensor regards this condition as the presence of an object near the door track. Based on this recognition, the auxiliary safety sensor holds the door open even if the activation sensor is turned off. The auxiliary safety sensor is effective, for example, when a person stops on the door track. In this situation, the activation sensor is turned off, because this person""s body is out of the interior and exterior detection ranges. Nevertheless, the auxiliary safety sensor can detect the person and keep the door open, thereby avoiding unexpected closure of the door.
As for installation of this type of auxiliary safety sensor, the transmitter and the receiver are equipped on the respective posts and have their signal lines passed inside the posts. Terminals at the ends of these signal lines are connected to a terminal block in an automatic door controller which is accommodated in a transom.
In order to enhance the reliability of object detection, this type of the auxiliary safety sensor may utilize two sensor sets, each of which is composed of a transmitter and a receiver. In a typical embodiment, the first sensor set (the first transmitter and the first receiver) and the second sensor set (the second transmitter and the second receiver) are provided at different heights. For this auxiliary safety sensor equipped with two sensor sets, the transmitters have their light emission timings (timings of generating light emission pulses) delayed from one another, in an attempt to ensure reliable light emission/acceptance actions at each sensor set (i.e. intended to prevent either receiver from operating in response to the light emitted from the other sensor set). In other words, the auxiliary sensor determines the absence of an object only when each receiver receives light in synchronization with the light emission timing of the opposite transmitter.
Regarding the installation of the auxiliary safety sensor with two sensor sets, two transmitters are equipped on one post and two receivers are mounted on the other post. Signal lines extending from these transmitters and receivers are passed inside the posts, so that each post contains two signal lines. Terminals (four terminals in total) at the ends of the signal lines are connected to a terminal block in an automatic door controller which is housed in a transom.
However, it is confusing to establish connection between the terminal block and the two signal lines passed inside each post. Namely, a worker may not be sure of the correlations between the transmitters and the signal lines in the first post (i.e. to find out which signal line comes from which transmitter), and the correlations between the receivers and the signal lines in the second post (i.e. to find out which signal line comes from which receiver). Thus, the sensor installation operation may end in misconnection, in which state the terminals are not connected to predetermined connection points at the terminal block in the automatic door controller. An example of misconnection is shown by the broken lines in FIG. 3 (the view showing how the transmitters 61, 62 and the receivers 63, 64 are connected to the terminal block 7). In this example, the signal line 63a coming from the first receiver 63 is connected to the connection point 74 for the second receiver 64, while the signal line 64a extending from the second receiver 64 is connected to the connection point 73 for the first receiver 63. In terms of signal processing, the first transmitter 61 and the second receiver 64 constitute a sensor set, and the second transmitter 62 and the first receiver 63 are paired as another sensor set, in a wrong manner. The transmitters and the receivers in these sensor sets are not opposed to each other. As a result, when the first receiver 63 receives a light beam produced at a given emission timing by the first transmitter 61, light acceptance data acquired by the first receiver 63 are inputted into the connection point 74 for the second receiver 64. Because this input does not coincide with a given acceptance timing, the sensor judges that no light is received. Similarly, when the second receiver 64 receives a light beam produced at a given emission timing by the second transmitter 62, light acceptance data acquired by the second receiver 64 are inputted into the connection point 73 for the first receiver 63. Because this input does not coincide with a given acceptance timing, the sensor judges that no light is received. While both sensor sets determine that the emitted light beams are interrupted by an object, the auxiliary safety sensor prohibits the closing action of the door, constantly leaving the door open. Unfortunately, it is impossible to notice the misconnection before an actual test operation of the automatic door. If misconnection is found by the operation test, a worker has to reconnect the signal lines, which complicates the sensor installation.
Various ideas have been suggested to prevent the misconnection. For one, signal lines of different colors can be employed. For another, tags can be attached to the signal lines in order to distinguish the sensor sets. In the former method, however, a worker has to bear a heavier burden of remembering the colors of the signal lines when he or she mounts the transmitters and the receivers on the posts. Besides, the latter method is detrimental to the operability, because the tags hinder the passage of the signal lines through the posts.
The invention is made in view of these problems and concerns a sensor for automatic doors which detects the presence of an object in an object detection area, with utilizing a plurality of sensor sets each being composed of a transmitter and a receiver. An object of the present invention is to correct misconnection of the transmitter and the receiver automatically, thereby ensuring the reliability of the detection performance of the sensor.
According to the present invention, the first solution for achieving the above object is based on a sensor for automatic doors having a plurality of sensor sets, each of the sensor sets being composed of transmission means and receiving means located opposite to each other across an object detection area, so that the sensor determines the presence or absence of an object within the object detection area, depending on whether a light beam emitted from each transmission means is received by the receiving means of the same sensor set. According to the first solution, this sensor is provided with data acquisition means and data exchange means. The data acquisition means is used to acquire light acceptance data sent from each receiving means. The data exchange means serves to exchange light acceptance data sent from one of the receiving means with those sent from any of the other receiving means, in order that the data acquisition means can acquire predetermined light acceptance data which concern a light beam emitted from one of the transmission means and which are received by the opposite receiving means. The data exchange action is carried out in the case where the data acquisition means fails to acquire the predetermined light acceptance data, provided that the transmission means emits a light beam in the absence of an object within the object detection area.
With this feature, if the data acquisition means fails to receive the predetermined light acceptance data while one of the transmission means emits a light beam, the sensor judges that the connection is improper. The misconnection can be automatically corrected by exchanging the light acceptance data with each other. Hence, a worker can engage in the connection operation without paying particular attention to the correlations between the transmitters and the signal lines or between the receivers and the signal lines. The sensor installation can be simplified in this way.
The second solution specifies the sensor structure. Based on the first solution, the second solution employs two such sensor sets. The data exchange means exchanges light acceptance data sent from one of the two receiving means with those sent from the other receiving means. This data exchange action is carried out in the case where the data acquisition means fails to acquire the predetermined light acceptance data, provided that either of the two transmission means emits a light beam in the absence of an object within the object detection area.
The third solution specifies the data exchange action. Based on the first solution, the third solution allows each of the transmission means to emit a light beam one by one. The data exchange means exchanges light transmission data sent from receiving means which receives the greatest amount of light, with those sent from receiving means located opposite to the transmission means which emits a light beam, in order that the data acquisition means can acquire the former data as the latter data. This data exchange action is carried out in the case where the data acquisition means fails to acquire the predetermined light transmission data, provided that each transmission means emits a light beam, by turns, in the absence of an object within the object detection area.
These features embody how to exchange the light acceptance data. Owing to the third solution, the data exchange action can be performed properly even if the sensor for automatic doors has more than two sensor sets. In this case, the transmission means can be related with the opposite receiving means by specifying the receiving means that receives the greatest amount of light.